Feature/available write

hal/inc/hal_dynalib_usart.h

@@ -60,6 +60,7 @@ DYNALIB_FN(hal_usart,HAL_USART_Peek_Data)
 DYNALIB_FN(hal_usart,HAL_USART_Flush_Data)
 DYNALIB_FN(hal_usart,HAL_USART_Is_Enabled)
 DYNALIB_FN(hal_usart,HAL_USART_Half_Duplex)
+DYNALIB_FN(hal_usart,HAL_USART_Available_Data_For_Write)
 
 DYNALIB_END(hal_usart)
 

hal/inc/usart_hal.h

@@ -72,6 +72,7 @@ void HAL_USART_Init(HAL_USART_Serial serial, Ring_Buffer *rx_buffer, Ring_Buffer
 void HAL_USART_Begin(HAL_USART_Serial serial, uint32_t baud);
 void HAL_USART_End(HAL_USART_Serial serial);
 uint32_t HAL_USART_Write_Data(HAL_USART_Serial serial, uint8_t data);
+int32_t HAL_USART_Available_Data_For_Write(HAL_USART_Serial serial);
 int32_t HAL_USART_Available_Data(HAL_USART_Serial serial);
 int32_t HAL_USART_Read_Data(HAL_USART_Serial serial);
 int32_t HAL_USART_Peek_Data(HAL_USART_Serial serial);

hal/src/core/usart_hal.c

@@ -218,6 +218,11 @@ void HAL_USART_End(HAL_USART_Serial serial)
   usartMap[serial]->usart_transmitting = false;
 }
 
+int32_t HAL_USART_Available_Data_For_Write(HAL_USART_Serial serial)
+{
+  return (unsigned int)(SERIAL_BUFFER_SIZE + usartMap[serial]->usart_tx_buffer->head - usartMap[serial]->usart_tx_buffer->tail) % SERIAL_BUFFER_SIZE;
+}
+
 uint32_t HAL_USART_Write_Data(HAL_USART_Serial serial, uint8_t data)
 {
   // interrupts are off and data in queue;

hal/src/gcc/usart_hal.cpp

@@ -7,6 +7,7 @@ struct Usart {
     virtual void begin(uint32_t baud)=0;
     virtual void end()=0;
     virtual int32_t available()=0;
+    virtual int32_t availableForWrite()=0;
     virtual int32_t read()=0;
     virtual int32_t peek()=0;
     virtual uint32_t write(uint8_t byte)=0;
@@ -84,6 +85,9 @@ class SocketUsartBase : public Usart
             fillFromSocketIfNeeded();
             return (rx->head-rx->tail) % SERIAL_BUFFER_SIZE;
         }
+        virtual int32_t availableForWrite() override {
+            return (SERIAL_BUFFER_SIZE + tx->head - tx->tail) % SERIAL_BUFFER_SIZE;
+        }
         virtual int32_t read() override {
             fillFromSocketIfNeeded();
             return read_char();
@@ -189,6 +193,11 @@ void HAL_USART_End(HAL_USART_Serial serial)
     //usartMap(serial).end();
 }
 
+int32_t HAL_USART_Available_Data_For_Write(HAL_USART_Serial serial)
+{
+    return usartMap(serial).availableForWrite();
+}
+
 uint32_t HAL_USART_Write_Data(HAL_USART_Serial serial, uint8_t data)
 {
     return usartMap(serial).write(data);

hal/src/stm32f2xx/usart_hal.c

@@ -311,6 +311,12 @@ int32_t HAL_USART_Available_Data(HAL_USART_Serial serial)
 	return (unsigned int)(SERIAL_BUFFER_SIZE + usartMap[serial]->usart_rx_buffer->head - usartMap[serial]->usart_rx_buffer->tail) % SERIAL_BUFFER_SIZE;
 }
 
+int32_t HAL_USART_Available_Data_For_Write(HAL_USART_Serial serial)
+{
+    return (unsigned int)(SERIAL_BUFFER_SIZE + usartMap[serial]->usart_tx_buffer->head - usartMap[serial]->usart_tx_buffer->tail) % SERIAL_BUFFER_SIZE;
+}
+
+
 int32_t HAL_USART_Read_Data(HAL_USART_Serial serial)
 {
 	// if the head isn't ahead of the tail, we don't have any characters

modules/shared/stm32f2xx/user_build.mk

@@ -56,7 +56,7 @@ LINKER_DEPS += $(SYSTEM_PART1_MODULE_PATH)/module_system_part1_export.ld
 
 NANO_SUFFIX ?= _nano
 
-LDFLAGS += -lnosys
+LDFLAGS += -lnosys --specs=nano.specs
 LDFLAGS += -L$(SYSTEM_PART2_MODULE_PATH)
 LDFLAGS += -L$(SYSTEM_PART1_MODULE_PATH)
 LDFLAGS += -L$(USER_PART_MODULE_PATH)
@@ -66,7 +66,7 @@ LDFLAGS += -Wl,--defsym,USER_FIRMWARE_IMAGE_LOCATION=$(USER_FIRMWARE_IMAGE_LOCAT
 LDFLAGS += -Wl,-Map,$(TARGET_BASE).map
 
 # used the -v flag to get gcc to output the commands it passes to the linker when --specs=nano.specs is provided
-# LDFLAGS += -lstdc++_nano -lm -Wl,--start-group -lgcc -Wl,--end-group -Wl,--start-group -lgcc  $(LIBG_TWEAK) -Wl,--end-group
+# LDFLAGS += -lstdc++$(NANO_SUFFIX) -lm -Wl,--start-group -lgcc -Wl,--end-group -Wl,--start-group -lgcc  $(LIBG_TWEAK) -Wl,--end-group
 
 BUILTINS_EXCLUDE = malloc free realloc
 CFLAGS += $(addprefix -fno-builtin-,$(BUILTINS_EXCLUDE))

user/tests/wiring/api/wiring.cpp

@@ -59,6 +59,11 @@ test(api_wiring_usartserial) {
     API_COMPILE(Serial1.halfduplex(true));
     API_COMPILE(Serial1.halfduplex(false));
 
+    API_COMPILE(Serial1.blockOnOverrun(false));
+    API_COMPILE(Serial1.blockOnOverrun(true));
+
+    API_COMPILE(Serial1.availableForWrite());
+
 }
 
 void TIM3_callback()

wiring/inc/spark_wiring_usartserial.h

@@ -35,6 +35,7 @@ class USARTSerial : public Stream
 {
 private:
   HAL_USART_Serial _serial;
+  bool _blocking;
 public:
   USARTSerial(HAL_USART_Serial serial, Ring_Buffer *rx_buffer, Ring_Buffer *tx_buffer);
   virtual ~USARTSerial() {};
@@ -43,6 +44,9 @@ class USARTSerial : public Stream
   void halfduplex(bool);
   void end();
 
+  virtual void blockOnOverrun(bool);
+
+  virtual int availableForWrite(void);
   virtual int available(void);
   virtual int peek(void);
   virtual int read(void);

wiring/src/spark_wiring_usartserial.cpp

@@ -32,6 +32,8 @@
 USARTSerial::USARTSerial(HAL_USART_Serial serial, Ring_Buffer *rx_buffer, Ring_Buffer *tx_buffer)
 {
   _serial = serial;
+  // Default is blocking mode
+  _blocking = true;
   HAL_USART_Init(serial, rx_buffer, tx_buffer);
 }
 // Public Methods //////////////////////////////////////////////////////////////
@@ -57,6 +59,17 @@ void USARTSerial::halfduplex(bool Enable)
     HAL_USART_Half_Duplex(_serial, Enable);
 }
 
+void USARTSerial::blockOnOverrun(bool block)
+{
+  _blocking = block;
+}
+
+
+int USARTSerial::availableForWrite(void)
+{
+  return HAL_USART_Available_Data(_serial);
+}
+
 int USARTSerial::available(void)
 {
   return HAL_USART_Available_Data(_serial);
@@ -79,7 +92,12 @@ void USARTSerial::flush()
 
 size_t USARTSerial::write(uint8_t c)
 {
-  return HAL_USART_Write_Data(_serial, c);
+  // attempt a write if blocking, or for non-blocking if there is room.
+  if (_blocking || HAL_USART_Available_Data_For_Write(_serial) > 0) {
+    // the HAL always blocks.
+	  return HAL_USART_Write_Data(_serial, c);
+  }
+  return 0;
 }
 
 USARTSerial::operator bool() {
@@ -98,4 +116,4 @@ static Ring_Buffer serial1_tx_buffer;
 
 USARTSerial Serial1(HAL_USART_SERIAL1, &serial1_rx_buffer, &serial1_tx_buffer);
 // optional Serial2 is instantiated from libraries/Serial2/Serial2.h
-#endif
+#endif